Friends of mine at a small casual SF convention did something very much in the spirit of these ideas.

They moved a chair, a small couch (loveseat), and some potted plants and ashtrays from the lobby areas near the elevator, into the elevator. One of them acted as a talk show host, and others as announcer, stagehand, and bandleader. Whenever someone got on the elevator, they'd invite them to sit on the couch, and then start interviewing them.

Then the rest of us moved the elevator-lobby couches on the remaining floors to be directly facing the elevator doors, and then sat in them and became TV viewers. When the elevator doors opened on a floor, the viewers on that floor would pretend they just tuned to that channel, and as they began closing, they'd pretend they were changing the channel.

There was one I saw on a hidden camera tv show... 3 people already in the lift would be joined by a random member of the public... once the doors closed the 3 people would all turn in unison to face another wall, and the other guy would follow suit. (hehe, with tv edits there's no idea what percentage of people actually did follow the others, but it's an interesting example of the herd mentality)

"Ankh-Morpork people, said the Guild, were hearty, no-nonsense folk who actually preferred chocolate made mostly from milk, sugar, suet, hooves, lips, miscellaneous squeezings, rat droppings, plaster, flies, tallow, bits of tree, hair lint, spiders and powdered cocoa husks. This meant that according to the food standards of Borogravia and Quirm, Ankh-Morpork chocolate was formally classed as 'cheese', and only escaped, through being the wrong colour, being defined as 'tile grout'."

a couple of ones:
stand with your nose just touching the join in the middle of the door. most people will be looking around and only register the door opening in the side of their vision. they will start to walk through and almost walk into you (often joined witha swark)
stand with your shoulders touching the doors, have a friend 'attacking' you as the doors open. fall backwards in full 'brawl' mode (or better yet have them running at you and you do the step aside trick, bonus points if they can run into another lift)